This is the Axlon RAMDISK 320, a Disk II-sized box that can connect to the Apple II (and reportedly also to the Apple III, with a different interface card) and serve as a fast RAM disk. It looks nice. Because I assembled this in pieces, I have not actually had a chance to test it out yet, but I think I am almost at a point where I can. I got the main unit itself a couple of years ago, and recently found the missing interface card. Earlier, someone else on eBay had sold a complete unit with a bunch of the disks, and was kind enough to make copies and send them to me. So, rather than wait until I finally get around to testing this all out, here is what I have so far.
Here is one of the ads.
And here is what the actual unit looks like. It is in a box essentially identical to a Disk II drive. Inside there are RAM chips and a battery, the board says designed by MOS Sorcery. Mine got kind of knocked around in shipping, and the fuse in the back basically shattered. I also have the card for the Apple II. There was a version of this for the Apple III as well, but it must have used a different card, since this card is too long to fit in the slot of an Apple III.
The disks that I got with the drive were v1.1 of the DOS System Master, and v1.0 of the Pascal system master.
From a helpful eBay seller, I was able to obtain copies of a bunch more disks. This is the photo of the disks he sent me, along with copies he made of them. There are two copies of v2.0 of the DOS system master, two more copies of the Pascal v1.0 system master, a copy of v1.0 of the DOS system master, some CP/M support files, two demo disks, and a disk that says it has the source code on it. Sadly, that source code disk had read errors. I will attempt some surgery on it to see what I can retrieve but it might be effectively lost. I have not tested these really at all. The DOS disk boots.
All of these disk images can be grabbed here: axlon-ramdisk320-disks.zip